The magnetometers are used to detect a foreign substance, the earth magnetism, the attitude of the mobile devices and so on. Recently the small type of magnetometers is equipped to mobile computer terminals such as mobile phones and smart phones. One of the typical types of these small magnetometers is the magneto impedance sensor equipped with a MEMS (Micro Electro Mechanical Systems) pickup coil operated by pulse current.
The magneto impedance sensor based on the magneto impedance effect (MI effect) which causes the change of the impedance of the magnetic wire having the compromise of CoFeSiB alloy especially which has amorphous wire proportional to the external magnetic field due to the surface effect of the high frequency current is one of the magnetometers. The type of the coil pickup is one of the magneto impedance sensor to detect the voltage induced in the pickup coil surrounded around the magnetic wire. The type of the pulse current operation is one of the magneto impedance sensor to use the pulse current instead of the high frequency current. The type of the coil pickup operated by the pulse current is called as MI sensor merely in the present invention. These MI sensor is referred in the following Japanese patent application and relating circuit.